Field of the Invention
The invention relates to a magnetic particle manipulation apparatus for performing chemical operations such as separation, extraction, purification, reaction, and so on of a target substance using magnetic particles.
Description of the Related Art
In monitoring or the like for medical examination, food safety and health management, and environmental conservation, a target substance is required to be extracted from a sample containing a great variety of impurities and then subjected to detection or reaction. For example, in medical examination, it is necessary to detect, identify and quantify nucleic acids, proteins, sugars, lipids, bacteria, viruses, radioactive substances and so on contained in blood, serum, cells, urine, feces and so on that are obtained by separation from animals and plants. During the examination of these substances, in order to eliminate bad influences of the background or the like caused by the impurities, it will sometimes be necessary to separate and purify the target substance.
In order to separate and purify a target substance in a sample, a method of using magnetic particles has been developed and put into practice which imparts chemical affinity with the target substance or a molecular recognition function to a surface of a magnetic having a particle diameter of around 0.5 μm to more than 10 μm. In this method, after the target substance is fixed to the surface of the magnetic particles, the magnetic particles are separated and recovered from the liquid phase by magnetic field manipulation; if necessary, steps of dispersing the recovered magnetic particles in the liquid phase of a cleaning solution or the like and separating and recovering the magnetic particles from the liquid phase are repeated. Thereafter, by dispersion of the magnetic particles in an eluent, the target substance fixed to the magnetic particles is released into the eluent, and the target substance in the eluent is recovered. By using magnetic particles, recovery of a target substance by means of a magnet becomes possible. Therefore, the method is advantageous in terms of automation of chemical extraction and purification.
The magnetic particles to which the target substance can be selectively fixed are commercially available as a part of a separation and purification kit. The kit includes a plurality of reagents placed in separate vessels. When the kit is in use, the user aliquots and dispenses the reagents with a pipette or the like. An apparatus for automating the pipetting operation or magnetic field manipulation is also commercially available (Patent Document 1). On the other hand, a method is proposed in which, instead of performing the pipetting operation, a tubular device in which a liquid layer such as a solution/fixing solution, a cleaning solution, an eluent or the like and a gel-like medium layer are alternately stacked with each other within a tubular vessel such as a capillary or the like is used, and the magnetic particles are moved within this device along a longitudinal direction of the vessel, thereby separating and purifying the target substance (Patent Document 2).